Circuit interrupter



.IW/Q. W

Dec. 17, 1945.

J. SLEPIAN 2,412,919

cIRcUIT-INTERRUPTER Filed March 27, 1943 2 vSheets-Shea?. l

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INVENTOR Josep/2 S/@p/'a/Z Patented Dec. 17, 1946 UNITED STATES PATENT GFFICE CIRCUIT INTERRUPTER Application March 27, 1943, serial 10.480.733

This invention relates to circuit interrupters in general, and, more particularly, to circuit interrupters of the type which utilize an aro extinguishing gas to effect-turbulence within the arcing region to assist in extinguishing the arc drawn during a circuit interrupter opening operation.

An object of my invention is to provide an improved circuit interrupter having cooperable electrodes, in at least one of which are disposed a plurality of gas conducting apertures.

Another object is to provide an improved circuit interrupter which' sends a plurality of gas jets at substantially acoustic velocity into the arcing region.

A further object is to provide 'an improved circuit interrupter which has cooperable perforated electrodes, and to send a plurality of gas jets at near acoustic velocity through the perforatlons or apertures in one electrode into the arcing region and out the perforations yor apertures in the other cooperable electrode also at near acoustic velocity to effect rapid extinction of the arc drawn between the electrodes.

Another object is to provide an improved circuit interrupter having at least one gas conducting pa-ssage through one electrode to' not only effect turbulence in the arcing region but also to Aeffect a lateral movement of the arc to distribute the heating effect of the terminal of the arc over the surface of the electrode.

A more speciiic object is to provide an improved circuit interrupter comprising a pair or cooper'- -able electrodes between which :an arc-may be established, and to provide gas conducting apertures in both electrodes inclined helically in opposite directions to effect both turbulence and lateral arc movement in the arcing'reg'ion between the electrodes.

Another object is to provide an annular arcing Vpassage between two cooperable electrodes in which the established arc may be moved laterally.

For purposes of illustration I describe my invention as applied to circuit interrupters of the 'compressed air type. Other gases such as carbon dioxide, hydrogen, etc., may, however, be used.

. .Further objects and advantages oi my inven- 'tion' will readily become apparent upon a reading ofthe following specification taken in conjunc tion withi the drawings, in which:

Figure 1` is a plan view of a circuit interruptor embodying my invention; Fig. 2 isa view in cross section line II--II of Fig. 1;

= Fig. 3 'is a view in cross section taken on the,

line vIII-III-oi' Fig. 2; 1

taken on the 1o claims. (o1. zoo- 148) Fig. 4 is an enlarged fragmentary plan view of the top fixed electrode looking down on the line IV-IV of Fig. 2;

' Fig. 5 is an elevational View, partly in section, of a circuit interrupter embodying a modication of my invention;

Fig. 6 is an inverted View in section taken on line VI--VI of Fig. 5; and f Fig. 7 is an inverted View in section taken on the line vri-vir of Fig. 5.

Referring to the drawings, and more particu- .larly to Fig. 2, the reference numeral I designates a fixed plate electrode to which a terminal 2 is rigidly attached. The fixed plate electrode I has Y'formed therein a plurality of exit apertures 3 inclined helically as more clearly shown in Figs. 3 and 4.

Cooperating with the xed plate electrode I is 4Va second fixed plate electrode 4 which has a conltubular conducting bridging electrode I 2.

4 and maintaining `themin spaced relation is an "insulating ring 8', more clearly shown in Fig. 2. Also disposed between' the plate electrode I, 4 is an insulating plate 9'. v'Ihreadedly secured to the `iixed plate electrode 4 ist an insulating tubular ared conduit member I0, which serves to 'con- =duct a suitable arc extinguishing gas, in this in- -stance compressed air, toward the inlet apertures "I' disposed in the fixed plate electrode 4, as shown more clearly by the arrows in Fig. 2.

The fixed plate electrode has an upstanding guide portion II which serves to guide a movable In the closed circuit position of the interruptor the movable tubular bridging electrode I 2 engages the lContact portion 5 of the fixed plate electrode 4 toelectrically connect the plate electrodes I, 4.

rConsequently,.the electrical ycircuit through the vinterrupter in the closed circuit position (not lsliowrn comprises the terminal 2, the fixed plate electrode l, the' movable tubular' bridging electrode I2 Contact portion 5 of 'fixed plate electrode 4 to the other terminal `6 of. the interruptor."

Exit apertures '3"a1'e' also provided in the movable tubular electrode I2 and also in the upstand- Referring to Figure 2 it will be observed that the insulating ring 8 cooperates with the insulating plate 9 to form an annular interelectrode arcing passage generally designated by the reference numeral I5 the ends of which are bounded by annular arcing members formed by the inwardly exposed surfaces of electrodes I and 4 respectively. The edge portions of the insulating ring 8 and insulating plate 9 adjacent the arcing passage I5 have apertures formed therein to align with the apertures 3, 'I of plate electrodes I, 4 as more clearly shown in Fig. 2. Positioning pins I8, as more clearly shown in Fig. 2, prevent rotation of the insulating plate 9A with respect to the fixed plate electrode 4.

helically inclined inlet apertures 'I of xed plate electrode 4 to result in a plurality of air jets which enter the annular interelectrode arcing passage I5 turbulently. The air flow through the inlet apertures I produces not only a very high turbulence in the annular passage I5, but also produces an angular momentum which causes a mass circulation of the air around the annular f interelectrode arcing passage I5 at high Velocity. The angular momentum carries the arc IB, which is initially established, rapidly around the annular arcing passage I5 on the extended surfaces of the plate electrodes,A I, 4.Y Fig. 3 shows the position of the arc I6 after it has been carried part way around the annular arcing passage I5 to a position designated by the reference numeral I'I.

I have found that for a circuit interrupter of the type shown in Figs. l-4 inclusive which is designed for 15,000 volts, 60 cycles, and large currents, thatA the pressure at the entrance. to the linlet apertures 'I in xed plate- 4 may be substan tially 60 pounds per square inch absolute pres- 7 sure. The total area of the inlet apertures I is approximately 1115 of the eiective area of the fixed plate electrode 4. The interelectrode pressure within the annular arcing passage I5 may be 30 pounds per square inch absolute pressure. T1

Consequently the air jets coming into the annular arcing passage I5 through the inlet apertures 'I in fixed plate electrode 4 will have substantially the velocity of sound-in air, that is 14,000 inches:

Der second. Y

The total area of the exit apertures 3 in fixed plate electrode I is substantially Tis of the eifective area of fixed plate electrode I. Atmospheric pressure, that is 15 pounds per square inch absolute pressure, prevails outside of the xed plate electrode I. Consequently the air jets which pass through the exit apertures '3 in xed plate electrode I will have substantially lthe velocityv of sound in air. The width between the plate elet4 trodes I. 4 may be approximately fa inch.

The arc I 6 is carried rapidly around the annular arcing passage I 5 at high velocity and permitted to play between the annular portions of the electrode plates I and relatively unimpeded and unrestricted. At a current zero the arc will not restrike because of the increase in dielectric strength of the air within the rannular interelectrode arcing passage I5 caused by the turbulence of the air jets passing through the inlet apertures 7 in plate electrode 4 at substantially acoustic velocity. Also the rotation of the arc I5 around the annular arcing passage I5 distributes the heating effect over the extended surfaces of he electrodes I, 6 to minimize the emission cf ionized metallic particles from the plate electrodes I, ll. rlhe .arc I 6 is extinguished-at the first current Zero, and suitable means not shown may then stop the compressed air ow.

In the embodiment of my invention shown in Figs. 5 through '7 inclusive there is provided a fixed tubular electrode 2l having a plurality of inlet apertures 22 preferably generally uniformly distributed across the face thereof. An insulating gas conduit 23 is threadedly secured to the fixed tubular electrode 2 I, and the passage of gas therethrough is controlled by the electrically actuated valve generally designated by the reference numeral 2d.

Surrounding the tubular electrode 2I is an insulating casing 25, in this instance cylindrical, which also serves as a guide for a movable tubular electrode 26. Terminal k2'I is rigidly secured to the fixed tubular electrode 2l, and a terminal 23 is rigidly secured to the movable tubular electrode 25 as 'more clearly shown in Fig. 5.

Consequently in the closed circuit positicnof the interrupter (not shown) the electrical circuit therethrough comprises terminal 28., movable tubular electrode 2S, xed tubular electrode 2I, to terminal 21.

Disposed in the movable tubular electrode 25 are a plurality of exit apertures 29 also preferably generally uniformly distributed across the face thereof. The reference numeral 30 generally designates the interelectrode arcing region.

During the opening operation of the interrupter shown in Fig. 5 the movable tubular elec.- trode 25 is moved upwardly to separate` from the fixedv tubular electrode. 2I to draw an arc 3l in the interelectrode arcing region 30 and which is permitted to play relatively` unimpeded and unrestricted between the electrodes 2l and 25 now serving as arc terminal members. Simultaneously, a suitable means (not shown) operates the electrically actuated' valve 25 to force a stream of gas, in this instance compressed air. upwardly through the insulating conduit 23 and upwardly through the inlet apertures 22 into the arcing region 30.

The compressed air jets passing through the xed tubular electrode 2l produce turbulence within the interelectrode arcing region 30 to extinguish the arc 3l at the first current zero. The direction of the compressed airV ilow is indicated by the arrows in Fig. 5.

For a circuit interrupter of the type shown in Fig. 5 designed for 15,000 volts, v60 cycles, and for high current, the separation between the fixed electrode 2l and the movable electrode 26 may be taken as l centimeter at arc extinction. The transient peak voltage which the arcing'region 20 must stand after current zero will be under-50 kv. This dielectric strength can be insured by providing that the compressed air in this space is at 30 pounds per square inch absolutelpres'- sure. After the transient it may fall to normal `pounds per square inch absolute pressure.

Compressed air is injected into the arcing region 30 at about acoustic velocity or 14,000 inches per second through the inlet apertures 22 in the fixed electrode 2| The driving pressure is then 60 pounds per square inch absolute. The area of the apertures 22 may be substantially il@ the area of the xed electrode 2l. The area of the exit apertures 29 in movable electrode 20 may be substantially 1%; of the electrode area. Therefore, the 30 pounds per square inch interelectrode pressure will discharge the air out through the exit apertures 2S in the movable electrode 26 at substantially acoustic velocity to atmospheric pressure.

The air between the electrodes 2l, 26 will be in a highly turbulent state. The intensity factor of the turbulence will be close to acoustic velocity, or 3.104 cm./sec. The scale factor of the turbulence will be about 0.5 cm. The eiective diffusion coefficient due to this turbulence will be of the order of the product of these factors or about 104.

The time constant for the decay of ionization and temperature in the interelectrode space will be where d is the interelectrode separation and D is the effective diffusion coefficient. Taking d=1 and D=104, this gives a time constant of 10 microseconds, which is fast enough to ensure arc extinction in any practical circuit.

Figs. 6 and 7 show a comparison of aperture areas provided in the electrodes 2|, 26.

Although I have shown an application of my invention to two different types of circuit interrupters operating at 15,000 volts, 60 cycles, and at high currents it is to be clearly understood that for higher or lower voltage ratings or currents the dimensions and also the pressure of the gas used would necessarily be varied to suit the operating conditions desired.

It will also be apparent that in both embodiments of my invention shown and described, the compressed air is injected in the form of a plurality of air jets at acoustic velocity into the arcing region, and is also exhausted out of the arcing region at acoustic velocity. Using compressed air as the arc extinguishing gas, the velocity of the air jets entering and leaving the arcing region should be in the range from 5,000 inches per second to 14,000 inches per second, the latter figure being the numerical value of acoustic velocity in air. My preferred range of velocities is, however, from 10,000 inches per second to 14,000 inches per second using compressed air.

For other gases the numerical value of the Velocity of sound is different from that in air. In hydrogen, for example, the velocity of sound is approximately four times that for air.

Using other gases than air, the range of velocities of the jets entering and leaving the arcing region should be between 30% and 100% of the velocity of sound in the gas used. The preferred range is from '70% to 100% of the velocity of sound in the gas used.

I have found that the ratio of the total inlet aperture area in the inlet electrode to the total exit aperture area in the exit electrode should be in the range from 1:1 to 1:3. My preferred range is between 1:11A to 1:21/2. In both embodiments shown in the drawings the ratio is 1:2 which gives the best results.

The pressure of the gas on the low pressure side of any of the electrodes I, 4, 2l, 26 should be from 1A to 3A, of the gas pressure on the high pressure side of the particular electrode. The preferred pressure is from 1)/8 to 578 of that on the high pressure side of the electrode. In the two breakers shown, the pressure on the low pressure side of any of the electrodes is 1/2 that on the high pressure side. This I have found to give the best results.

Although I have shown and described specific structures it is to be clearly understood that the same were merely for purposes of illustration, and that changes and modifications may readily be made by those skilled in the art without departing from the spirit and scope of the invention. L'

I claim as my invention:

l. In a circuit interrupter, a pair of relatively movable electrodes between which an arc is established, means forming an annular arcing passage disposed between the electrodes, an annular arcing member disposed at each end of said arcing passage and between which said arc is adapted to be moved relatively unimpeded and unrestricted, said arcing members having a plurality of gas conducting apertures formed therein, and means forcing gas under pressure at high velocity unidirectionally through said apertures and said. arcing passage to create a highly turbulent atmosphere therein for extinguishing the arc.

2. In a circuit interrupter, a pair of electrodes between which an arc is established, at least one of the electrodes having a plurality of gas conducting aperturesformed therein which are inclined helically.

3. In a circuit interrupter, a pair of cooperable electrodes between which an arc may be established, both electrodes having formed therein a plurality of gas conducting apertures, the apertures in the pair of electrodes being inclined helically in opposite directions.

4. In a circuit interrupter, a pair of cooperable eiectrodes between which an arc may be established, at least one electrode being substantially fiat and having one gas conducting aperture therein which is inclined with respect to the longitudinal axis of the electrode.

5. In a circuit interrupter, a relatively fixed tubular electrode closed at one end except for a plurality of apertures disposed therein, a oooperable movable tubular electrode also closed at one end except for a plurality of apertures disposed therein, a relatively tight fitting insulating casing surrounding the fixed electrode and also serving as a guide for the movable electrode and forming an arcing region between the apertured surfaces of said electrodes, and means for forcing gas through the apertures in the fixed electrode into the arcing region and out through the apertures in the movable electrode at a rate to create within the arcing region a turbulent atmosphere having a high coeflicient of diffusion to quickly extinguish the arc drawn between the electrodes.

6. In a circuit interrupter, a pair of electrodes between which an arc is established, means forming an annular arcing passage disposed between the electrodes, at least one of the electrodes having a plurality of gas conducting apertures formed therein which are inclined helically.

'7. In a circuit interrupter, a pair of electrodes between which an arc is established, means forming an annular arcing passage disposed between v'.aeraa-le .arc extinguishing gas fat .high velocity Vthrough said inlet passages :to `crea-gte .a highly turbulent atmosphere Within said chamber, .said other arc terminal member -'having .a plurality of generally uniformly distributed gas exhaust passages therethrough the total cross-,sectional area vof which y is .such to' enable ysaid gas to exhaust from said chamber lat a vvelocity substantially equal to the inlet velocity to enhance the turbulence within 'the are chamber and bring .about a rapid ,diffuvsion of Aions .and .quickly extinguish the arc.

9. In a circuit interrupter, a tubular member of insulating material, a pair of arc terminal members .of conducting material adapted to be .positioned in .spaced relation within said tubular member .to provide rend walls of an arcing chamfber, one of said arc terminal members having a plurality of gas inlet openings therethrough, the other of Vsaid are :terminal members 'having a .plurality of gas exhaust :openings therethrough, means for establishing `an '.arc. between said arc terminal members, and means for causing fa y'high vVelocity blast of gas `to flow longitudinally through said tubular vmember, said'inlet openings insaid one arc terminal member causing ahig-h degree of turbulence in said arc chamber, said exhaust openings in said other arc terminal member being so proportioned `with respect ,to :said inlet openings to .cause said gas to exhaust :therethrough at substantially` the same Velocity ras .the gas entering lsaid chamber to .enhance the turbulent effect 'in .the :arc chamber to quickly deionize and extinguish the arc :and to maintain the gas :therein -at a predetermined pressure.

10. In a circuit interrupter of the compressed gas type, a .pair of spaced generally iiiat `arcterminal members between which `an arc is adapted to play, tubular tmeans rof insulating material extending 'between said arc terminal members Lto dei-lne .therewith an .arc chamber, `said arc terminal :members having `a .plurality of apertures therein to permit va unidirectional flow of gas through said arc chamber, means forestablishing an .arc .between said farc terminal members, and means :for moving gasunder suiiicient pressure to produce a iiow through said apertures of the order of 30% to 100% acoustic velocity, said apertures being so arranged to produce within said arc chamber a highly turbulent atmosphere having a high effective diusion coecient to quicklyextinguish the arc.

JOSEPH SLEPIAN. 

